1. Field of Invention
This invention relates to cardiac catheters, more particularly, this invention relates to a specialized catheter to be used in the coronary sinus of the heart.
2. Prior Art
Catheters have been in use in medical procedures for many years. For example, they can be used to convey an electric stimulus to a selected location within the human body. Further, they can be used to monitor and make measurements for diagnostic tests of activities within the human body. Such catheters examine, diagnose and treat while positioned at a specific location inside the human body which are otherwise inaccessible without more invasive procedures. Recently, catheters have become more commonly used within the human heart and vascular system. In such use, the catheter is first inserted into a major vein or artery which is near the body surface. The catheter is then guided to the area for diagnosis or treatment by manipulating the catheter through the vessels of the body. As the utilization of catheters in remote and difficult to reach portions of the body including the heart has increased, it has become important to control precisely the movement of the catheter.
Control of the movement of catheters is difficult because of the inherent structure of the catheter. The body of conventional catheters is long and tubular. To provide sufficient control over the movement of the catheter, it is necessary that its structure be somewhat rigid. However, the catheters must not be so rigid as to prevent navigation of the catheter through the body vessel to arrive at the precise location where the medical procedure will be performed. In addition, it is imperative that the catheter not be so rigid as to cause damage to the body vessel through which it is being passed.
While it is important that the catheter not be so rigid as to cause injury to vessels and arteries, it is also important that there be sufficient rigidity in the catheter to accommodate torque control, i.e., the ability to transmit a twisting force along the length of the catheter. Sufficient torque control enables controlled maneuverability of the catheter by the application of a twisting force at the proximal end of the catheter that is transmitted along the catheter to its distal end. The feature of existing catheters which provides greater torque control often conflicts with the need for reduced rigidity to prevent injury.
One common method of addressing this problem has been the use of catheters with decreasing levels of rigidity through the length of the catheter, particularly through the use of a "soft" tip at the distal end of the catheter. See, for example, U.S. Pat. Nos. 4,385,635, 4,886,506, 5,122,125, 4,563,181, 4,863,442, 4,753,756, 4,636,346 4,898,591 and 4,596,563.
As above stated, catheters are used increasingly for medical procedures involving the human heart. In these procedures, the catheter being used is typically guided to the heart through vessels including arteries, veins, and cardiac chambers and then it is placed at a precise location within the heart. Typically, the catheter is inserted in an artery or vein in the leg, neck, upper chest or arm of the patient and threaded, often with the aid of a guidewire in the catheter, through various arteries and veins until the tip of the catheter reaches the desired location. The distal portion of the catheter may be preformed into a desired curvature so that by torquing the catheter about its longitudinal axis, the catheter can be manipulated to the desired location within the heart. For example, U.S. Pat. No. 4,882,777 discloses a catheter with a complex curve at its distal end for specific procedures in the right ventricle of a human heart. Further, U.S. Pat. No. 4,117,836 discloses a catheter for the selective coronary arteriography of the left coronary artery and U.S. Pat. Nos. 5,016,640 and 4,883,058 disclose catheters for the use in the right coronary artery. In addition, U.S. Pat. No. 4,898,591 discloses a catheter with inner and outer layers containing braided portions. That patent discloses a number of different curvatures of intervascular catheters.
Unfortunately, none of the disclosed products are adequate for use in the coronary sinus of the heart. The coronary sinus is the largest cardiac vein and runs along the atrioventricular groove and empties into the right atrium. Thus, new catheters designed specifically for use within the coronary sinus are necessary.
Accordingly, it is an object of this invention to prepare a catheter designed for ease of access of, and for use in the coronary sinus.
Another object of this invention is to prepare a fixed shaped catheter for use in the coronary sinus which can provide electrophysiological sensing for various locations within the coronary sinus.
It is a still further object of this invention to provide a fixed shape coronary sinus catheter which can sense electrical activity in and/or deliver electric energy to the right and left atria as well as the left ventricle.
These and other objects are obtained by the design of the coronary sinus catheter of the instant invention.